Abstract:

In view of the technical problems of Jilantai Salt Lake in Inner Mongolia such as difficulty in replenishing freshwa-ter,high sulfate content in the two-layer salt and difficulty in post-treatment of ammonia-alkali wastewater,the process of preparing liquid salt by mixing two-layer salt saturated brine with ammonia alkali waste liquid and the process of preparing liquid salt by dissolving two-layer salt after mixing ammonia alkali waste liquid with distilled water were studied,respectively.From the online Raman experiment,it was measured that the reaction took more than 1 h to reach equilibrium.The ef-fect of mechanical stirring rate,chemical reaction time,mixing ratio of ammonia alkali waste liquid and distilled water on the contents of NaCl,SO₄^2- and Ca²⁺ in liquid salt were investigated.The results showed that the reaction process of CaCl₂ and Na₂SO₄ was the rate controlling step of CaSO₄·2H₂O reaction crystallization process under the conditions of the molar ratio of SO₄^2- and Ca²⁺ was 1∶1,25 ℃,300 r/min.Under the same conditions,it took more than 120 minutes to produce the liquid salt of guaranteed reagent during the technology route of preparing liquid salt by mixing two-layer salt saturated brine with ammonia alkali waste liquid.In the the process of preparing liquid salt by dissolving two-layer salt after mixing ammonia alkali waste liquid with distilled water,under the conditions of volume ratio of ammonia-alkali waste liquid to freshwater was1∶（5.55~6.36）,25 ℃,300 r/min,the optimal liquid salt was obtained by separation after reaction for 120 min.

Key words: two-layer salt, ammonia-alkali wastewater, liquid salt